Australia's prime minister calls for global social media restrictions after Christchurch shootings

• Australian Prime Minister Scott Morrison has called for a global crackdown on social media in the wake of the attacks last week at two mosques in Christchurch, New Zealand.
• In a letter to Japan's Prime Minister, Morrison called for global leaders to take measures at their upcoming G-20 meeting in Osaka.
• The calls come after Facebook acknowledged that livestreamed footage of last Friday's attacked was viewed 4,000 times before it was removed.

Prime Minister Scott Morrison addresses the Australia-Israel Chamber of Commerce on March 18, 2019 in Melbourne, Australia.

Quinn Rooney | Getty Images

Australian Prime Minister Scott Morrison has called for a global crackdown on social media after footage of last Friday's mosque attacks in Christchurch, New Zealand was livestreamed on Facebook, calling into question the extent to which the world's biggest tech giants can successfully monitor their own platforms.

In a letter to Japan's Prime Minister Shinzo Abe, Morrison asked the G-20 chair to make the issue central to the world leaders' upcoming summit in Osaka in June.

Morrison shared the letter in a Twitter post on Tuesday.

I've written to Japanese PM @AbeShinzo as G20 President to have the leaders of the world's biggest economies ensure social media companies implement better safeguards to ensure their platforms can't be exploited by terrorists or to spread hate speech.

"It is unacceptable to treat the internet as an ungoverned space," the Morrison's letter read.

"It is imperative that the global community works together to ensure that technology firms meet their moral obligation to protect the communities which they serve and from which they profit."

Facebook and Alphabet's YouTube are among those to have faced heavy criticism for their failure to block videos of last week's twin shootings, which left 50 dead and several others critically injured.

Facebook confirmed on Monday that a livestreamed video apparently showing last week's attack was viewed 4,000 times before it was removed.

During the livestream itself, the video was viewed fewer than 200 times, but views racked up after news of the attack broke. The footage was later shared on other platforms, including YouTube and Twitter.

Facebook said on Saturday that it removed 1.5 million videos of the attack in the first 24 hours after it was originally livestreamed. Facebook said 1.2 million of those videos "were blocked at upload." Reddit, Twitter and YouTube also tried to move quickly to remove content related to the shooting.

—CNBC's Arjun Kharpal contributed to this report.